Black screen but picture flashes on every 30 seconds.
This sounds like a power supply issue. TVs operate on DC current and therefore must have a power supply board to invert AC house current to DC as well as regulate the DC current supplied. Heat is created by this process and therefore certain components on power supply boards are prone to failure due to repeated overheating. I would suspect capacitors on the power supply board are failing so they are only able to store enough power to allow the video board to work every 30 seconds and then it shuts off again. You can replace the whole board but I have repaired these before for a few dollars and some soldering.
Kds-55a2020 video on off saoun ok sony
SOURCE: Picture blinking to black every 5-10 seconds. No
Your tv is a CRT projection one - in which the image is generated by 3 small tv tubes. Because of that there can be 4 causes for your problem:
1 - the high voltage supply (125v) to the horizontal deflection unit from the power source is unstable - the corresponding components (capacitors and rectifying diodes) will have to be checked and replaced.
2 - the very high tension coming from the flyback transformer discharges before reaching the tubes - you will need to find the location of the discharge (it will be a small spark) and make the distance between the components larger.
3 - the cables that carry the signals and the power to the video board (the board in which the tubes are plugged in) have a faulty contact - current flows thru them, they heat and expand, the contact is broken, the current stops = the screen goes black, they cool and contract, the contact is made, the current starts to flow = the image appears and the cycle repeats. You will need to check them all .
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